Mounting a sensor module to an unmanned ground vehicle

ABSTRACT

An unmanned ground vehicle includes a main body, a drive system supported by the main body, a manipulator arm pivotally coupled to the main body, and a sensor module. The drive system includes right and left driven track assemblies mounted on right and left sides of the main body. The manipulator arm includes a first link coupled to the main body, an elbow coupled to the first link, and a second link coupled to the elbow. The elbow is configured to rotate independently of the first and second links. The sensor module is mounted on the elbow.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/900,335 filed Feb. 20, 2018 and entitled “MOUNTING A SENSOR MODULE TOAN UNMANNED GROUND VEHICLE,” which is incorporated herein by referencein its entirety.

U.S. patent application Ser. No. 15/900,335 filed Feb. 20, 2018 claimspriority to and the benefit of U.S. Provisional Patent Application No.62/461,118 filed Feb. 20, 2017 and entitled “MOUNTING A SENSOR MODULE TOAN UNMANNED GROUND VEHICLE,” which is hereby incorporated by referencein its entirety

BACKGROUND

This specification relates generally to mobile robots and manipulatorarms for mobile robots. Modern day warfighters, law enforcementpersonnel, and rescue personnel have a need to employ unmanned groundrobots for various missions. Missions may vary in their requirements onthe unmanned ground vehicle and thus the capability for the warfighterto easily and rapidly modify the system, sometimes in the field, toachieve their mission objectives can be critical.

SUMMARY

An unmanned ground vehicle includes a main body, a drive systemsupported by the main body, a manipulator arm pivotally coupled to themain body, and a sensor module. The drive system includes right and leftdriven track assemblies mounted on right and left sides of the mainbody. The manipulator arm includes a first link coupled to the mainbody, an elbow coupled to the first link, and a second link coupled tothe elbow. The elbow is configured to rotate independently of the firstand second links. The sensor module is mounted on the elbow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example mobile robotic vehicle;

FIG. 2 is a side view the example robot in a morphology having amanipulator arm;

FIG. 3 is a perspective view of the robot illustrating components of themanipulator arm;

FIGS. 4A-B show examples of robots with the manipulator arm in a stowedposition;

FIGS. 5A-E show examples or robots with the manipulator arm deployed anda sensor module mounted to an elbow of the manipulator arm;

FIGS. 6A-B illustrate examples of the robot with the sensor modulemounted at a distal end of a manipulator arm;

FIGS. 7 A-C illustrate examples of the robot in a configuration wherethe manipulator arm includes a first link and an elbow and lacks asecond link; and

FIG. 8 is a flow chart of an example method for operating an unmannedground vehicle.

DETAILED DESCRIPTION

FIG. 1 illustrates an example mobile robotic vehicle 100 that may beused as an unmanned ground vehicle capable of conducting operations invarious environments such as urban terrain, tunnels, sewers, and caves.Moreover, the robot 100 may aid in the performance of urbanIntelligence, Surveillance, and Reconnaissance (ISR) missions,chemical/Toxic Industrial Chemicals (TIC), Toxic Industrial Materials(TIM), and reconnaissance. Although the robot 100 shown includes a trackdriven drive system having flippers, other mobility platforms,configurations and morphologies are possible as well, such as wheeldriven platforms, crawling or walking platforms, and so on.

The robot 100 can be designed to move about in a variety ofenvironments, including an urban environment of buildings (includingstaircases), streets, underground tunnels, building ruble, and invegetation, such as through grass and around trees. The robot 100 mayhave a variety of features which provide robust operation in theseenvironments, including impact resistance, tolerance of debrisentrainment, and invertible operability.

The robot 100 includes a main body 110 (or chassis) having a drivesystem 115 supported by the main body 110. The main body 110 has rightand left sides 110 a, 110 b as well as a leading end 110 c, a trailingend 110 d and a center of gravity CG_(M). In the example shown, the mainbody 110 includes right and left rigid side plates 112 a, 112 b disposedparallel to each other. At least one transverse support 114 rigidlycouples the right side place 112 a to the left side plate 112 b. Therigid components are designed for strength and low weight and can bemade from a material such as 7075-T6 aluminum. Alternative versions ofthe robot 100 can use other materials, such as other lightweight metals,polymers, or composite materials. The robot 100 may be electricallypowered (e.g. by a bank of standard military BB-2590 replaceable andrechargeable lithium-ion batteries).

In some implementations, the drive system 115 includes right and leftdriven track assemblies 120 a, 120 b (also referred to as the maintracks 120) mounted on the corresponding right and left sides 110 a, 110b of the main body 110 and having right and left driven tracks 122 a,122 b respectively. Each driven track 122 a, 122 b is trained about acorresponding front wheel, which rotates about a drive axis 15. Althoughthe robot 100 is depicted as having skid steer driven tracks, otherdrive systems are possible as well, such as differentially drivenwheels, articulated legs, and the like.

The robot 100 includes at least one extendable flipper 130 mounted onthe main body 110. In some examples, the robot 100 is configured toreleasably receive one or more flippers 130 onto the main body 110(e.g., onto and concentric with one of the front drive wheels at theleading end 110 c of the main body 110). As shown in FIG. 1, the robot100 includes right and left flippers 130 a, 130 b, which are shown in anextended configuration extending beyond the front or leading end 110 cof the main body 110.

The flippers 130, 130 a, 130 b each have a distal end 130 c, a pivot end130 d, and a flipper center of gravity CG_(F) between the distal andpivot ends 130 c, 130 d. Each flipper 130, 130 a, 130 b pivots about thedrive axis 15 near the leading end 110 c of the main body 110. Moreover,each flipper 130, 130 a, 130 b may have a driven flipper track 140, 140a, 140 b trained about flipper drive wheel 142 a, 142 b, which is drivenabout the drive axis 15 at the pivot end 130 d of the flipper 130 a, 130b.

In the example shown, flipper track supports 134 disposed on a flipperside plate 132 of the flipper 130 support the corresponding flippertrack 140. In some implementations, the flippers 130, 130 a, 130 b canbe rotated in unison in a continuous 360 degrees between a stowedposition, in which the flippers 130 a, 130 b are next to the right andleft side plates 112 a, 112 b of the main body 110, and at least onedeployed position, in which the flippers 130 a, 130 b are pivoted at anangle with respect to the main tracks 122 a, 122 b. The center ofgravity CG_(R) of the robot 100 can be contained within an envelope ofthe 360 degree rotation of the flippers 130 a, 130 b.

In some implementations, the flipper side plates 132 of the respectiveright and left flippers 130 a, 130 b are rigidly coupled to one anotherthrough the articulator shaft to move together in unison. In otherimplementations, the flippers 130 a, 130 b pivot independently of eachother. The combination of main tracks assemblies 120 a, 120 b andflippers 130, 130 a, 130 b provide an extendable drive base length tonegotiate gaps in a supporting surface. In some examples, the right maintack 122 a and the right flipper track 140 a are driven in unison andthe left main tack 122 b and the left flipper track 140 b are driven inunison to provide a skid steer drive system.

The main body 110 may include one or more cameras 118 disposed near theleading end 110 c of the main body 110 and may be positioned to have afield of view directed forward and/or upward. The camera(s) 118 maycapture images and/or video of the robot environment for navigating therobot 100 and/or performing specialized tasks, such as maneuveringthrough tunnels, sewers, and caves, etc.

The robot 100 may include one or more robotic manipulator arms 150(e.g., articulated arms) each having a pivot end 150 p pivotally coupledto the main body 110 and a distal end 150 d that may be configured toreceive a head 160 or a gripper 170 or both. The arm 150 may be coupledto the main body 110 in a manner that allows the arm 150 to be stowedalong the main body 110 in a compact configuration and pivot away frommain body 110 to allow a wider range of CG-shifting, for example, tonegotiate obstacles.

As shown in FIG. 1, a head 160 and a gripper 170 are mounted on thedistal end 150 d of the arm 150. The arm 150 has an arm center ofgravity CG_(A) and the head 160 has a center of gravity CG_(H). The head160 may include a camera 162 (e.g., visible light and/or infraredcamera), radar, LIDAR (Light Detection And Ranging, which can entailoptical remote sensing that measures properties of scattered light tofind range and/or other information of a distant target), LADAR (LaserDetection and Ranging), a communication device (radio frequency,wireless, etc.), and/or other components.

To achieve reliable and robust autonomous or semi-autonomous movement,the robot 100 may include a sensor system having several different typesof sensors. The sensors can be used in conjunction with one another tocreate a perception of the robot's environment (i.e., a local sensoryperception) sufficient to allow a control system for the robot 100 todetermine actions to take in that environment. The sensor system mayinclude one or more types of sensors supported by the robot body 110,which may include obstacle detection obstacle avoidance (ODOA) sensors,communication sensors, navigation sensors, and so on.

For example, these sensors may include proximity sensors, contactsensors, cameras (e.g., volumetric point cloud imaging,three-dimensional (3D) imaging or depth map sensors, visible lightcamera and/or infrared camera), sonar (e.g., ranging sonar and/orimaging sonar), radar, LIDAR (Light Detection And Ranging, which canentail optical remote sensing that measures properties of scatteredlight to find range and/or other information of a distant target), LADAR(Laser Detection and Ranging), laser scanner, ultrasound sensor, and soon.

In some implementations, the robot 100 includes a robot controller 200in communication with the drive system 115, the arm 150, and any head(s)160 or gripper(s) 170 mounted on the arm 150. The robot controller 200may issue drive commands to one or more motors driving the main tracks120 and the flipper tracks 140. Moreover, the robot controller 200 mayissue rotational commands to a flipper motor 135 to rotate the flippers130 about the drive axis 15. The robot controller 200 may include one ormore computer processors and associated memory systems.

The robot controller 200 may be implemented in hardware, software,firmware, or combinations of hardware, software and/or firmware. In someexamples, the robot controller 200 may be implemented using anon-transitory computer readable medium storing computer executableinstructions that when executed by one or more processors of a computercause the computer to perform operations. Computer readable media mayinclude non-transitory computer-readable media, such as disk memorydevices, chip memory devices, programmable logic devices, random accessmemory (RAM), read only memory (ROM), optical read/write memory, cachememory, magnetic read/write memory, flash memory, and applicationspecific integrated circuits. In addition, a computer readable mediumthat implements the robot controller 200 may be located on a singledevice or computing platform or may be distributed across multipledevices or computing platforms.

The proximity sensors may be converging infrared (IR) emitter-sensorelements, sonar sensors, ultrasonic sensors, and/or imaging sensors(e.g., 3D depth map image sensors) that provide a signal to a robotcontroller 200 when an object is within a given range of the robot 100.The robot controller 200 (executing a control system) may executebehaviors that cause the robot 100 to take an action, such as changingits direction of travel, when an obstacle is detected.

In some examples, the sensor system includes an inertial measurementunit (IMU) in communication with the robot controller 200 to measure andmonitor a moment of inertia of the robot 100 with respect to the overallcenter of gravity CGR of the robot 100. The robot controller 200 maymonitor any deviation in feedback from the IMU from a threshold signalcorresponding to normal unencumbered operation. For example, if therobot begins to pitch away from an upright position, it may be “clotheslined” or otherwise impeded, or someone may have suddenly added a heavypayload. In these instances, it may be necessary to take urgent action(including, but not limited to, evasive maneuvers, recalibration, and/orissuing an audio/visual warning) in order to assure safe operation ofthe robot 100.

When accelerating from a stop, the robot controller 200 may take intoaccount a moment of inertia of the robot 100 from its overall center ofgravity CGR to prevent robot tipping. The robot controller 200 may use amodel of its pose, including its current moment of inertia. Whenpayloads are supported, the robot controller 200 may measure a loadimpact on the overall center of gravity CGR and monitor movement of therobot moment of inertia. If this is not possible, the robot controller200 may apply a test torque command to the drive system 115 and measureactual linear and angular acceleration of the robot using the IMU, inorder to experimentally determine safe limits.

The robot controller 200 may include a communication system 202, whichincludes, for example, a radio to communicate with the remote operatorcontrol unit (OCU) 50 to receive commands and issue status and/ornavigation information. The OCU 50 may include a display 52 (e.g., LCDor touch screen), a keyboard 54, and one or more auxiliary user inputs56, such a joystick or gaming unit. The OCU 50 may also include acomputing processor and memory in communication. The processor isprogrammed for rendering graphics on the display 52. The OCU 50 allowsan operator or user to control the robot 100 from a distance.

In some examples, the user can select different levels of human controlover the robot 100, ranging from a teleoperation mode, in which the userdirectly controls the motors and actuators on the robot 100, toautonomous operation, in which the user passes higher-level commands tothe robot 100. In partially autonomous operation, the robot 100 canperform tasks such as following a perimeter or wall, recovering fromgetting stuck in an opening or due to high centering on an obstruction,evading a moving object, or seeking light.

The robot controller 200 can be mounted in any appropriate location onthe robot 100. In some implementations, the robot controller 200 ismounted on the main body 110 in a location spanning between the drivetracks or wheels. The main body 110 may include a control electronicshousing that is part of the main body 110, i.e., integrated into theshape of the main body 110. This morphology results in the arm 150payload being positioned on top of the control electronics housing. Thisarrangement increases the vertical height of the robot 100 when the arm150 is installed. Alternatively, the robot controller 200 can be locatedin another location to open more space for the arm 150.

FIG. 2 is a side view the example robot 100 in a morphology having amanipulator arm 150. The manipulator arm 150, as illustrated in thisexample, has seven degrees-of-freedom (DOF). FIG. 2 shows a kinematiclayout of the manipulator arm 150. The kinematic chain goes, from themain body to the end of the manipulator:yaw-pitch-pitch-pitch-pitch-roll-grip. The manipulator arm 150 isconfigured to move according to the kinematic chain by virtue of aplurality of electronically-controlled motors, e.g., one motor for eachDOF.

The robot 100 includes a sensor module 400, e.g., an Intelligence,Surveillance, and Reconnaissance (ISR) sensor module. The sensor module400 can include a number of sensors and appropriate processing circuitryfor operating the sensors. For example, the sensor module 400 caninclude one or more cameras and digital circuits for producing videofeeds from the cameras suitable for digital recording and/ortransmission to a remote operator control unit. The sensor module 400can include other sensors, e.g., proximity sensors, contact sensors, andother sensors as described above with reference to FIG. 1.

The sensor module 400 can be simply and rapidly repositioned at multiplelocations on the robot 100 depending on the operator requirements. Thesensor module 400 can be repositioned by virtue of multiple mounts forthe sensor module 400, e.g., at multiple locations on the manipulatorarm 150. The robot 100 may be further modular in that the robot 100 mayinclude optional camera mounts at the front and back of the robot andthe gripper 170 may include releasable gripper fingers, e.g., gripperfingers that are sized to grip onto gripper finger mounts for tool-lessremoval or insertion in the field.

FIG. 3 is a perspective view of the robot 100 illustrating components ofthe manipulator arm 150. The manipulator arm 150 has a first link 150 apivotally coupled to the main body and a second link 150 b that receivesa gripper 170. The second link 150 b is pivotally coupled to the firstlink 150 a by way of an elbow 150 c housing a motor for pivoting thesecond link 150 b. The manipulator arm 150 also includes a turret 150 t.

Although the manipulator arm 150 is illustrated in this example with twolinks 150 a-b, in general, the manipulator arm 150 may have anyappropriate number of links. A sensor module can be mounted on an elbowbetween any two of the links. The elbow can be controllableindependently of the two links to allow for movement of the sensormodule independently from the links.

In some examples, the elbow 150 c includes an elbow motor forcontrolling a rotational orientation of the elbow 150 c independentlyfrom the first and second links 150 a-b. By virtue of the elbow motor,the sensor module 400 can be rotated to face further up or down or tomaintain a horizontal orientation with respect to the robot 100 even asthe manipulator arm 150 is extended or retracted to various positionsbetween a fully extended position and a stowed position.

In some examples, the first link 150 a includes a first motor forrotating the elbow 150 c and the second link 150 b includes a secondmotor for pivoting the second link 150 b about the elbow 150 c. Thefirst and second motors work together to determine the position of thesensor module 400 and the second link 150 b with respect to the firstlink 150 a. In some other examples, the manipulator arm 150 includes adedicated elbow motor for rotating the elbow 150 c, i.e., a dedicatedelbow motor separate from first and second motors for pivoting the firstand second links 150 a-b.

The manipulator arm 150 includes a first mount for the sensor module 400on the elbow 150 c and a second mount for the sensor module 400 on topof the gripper 170. The sensor module 400 may include multiple matchingmounting features. For example, suppose that the sensor module 400 ismounted to the elbow 150 c by, e.g., bolts or straps or both. The sensormodule 400 may also include a picatinny mounting clamp that allows thesensor module 400 to be placed on any picatinny rail. The manipulatorarm 150 may have a second mount for the sensor module 400, e.g., as apicatinny rail 420 on top of the gripper 170.

FIGS. 4A-B show examples of robots with the manipulator arm in a stowedposition. FIG. 4A is a side view 450 of a robot in a morphology withboth front and back flippers. The sensor module 400 is mounted to anelbow of the manipulator arm and then stowed with the manipulator armwithin a volume between the tracks of the robot. In this position, boththe sensor module 400 and the manipulator arm are stowed entirely withinthe volume between the tracks.

FIG. 4B shows a side view 452 and a perspective view 454 of a robot in amorphology with front flippers and a manipulator arm mounted forward,i.e., mounted closer to the front end of the main body and the flippersthan the back end of the main body. The robot includes one or moreoptional telescoping antennas 456.

FIGS. 5A-E show examples or robots with the manipulator arm deployed anda sensor module mounted to an elbow of the manipulator arm. FIG. 5Ashows a side view 550 and a perspective view 552 of the robot in amorphology with both front and back flippers. FIG. 5B shows a left sideview 554 and a right side view 556 of the robot in a morphology withfront flippers and a manipulator arm mounted forward. FIG. 5C shows aside view 558 and a perspective view 560 illustrating the location ofthe turret 150 t, which is mounted low enough in the volume between thetracks so that the manipulator arm and the sensor module can fit intothe volume between the tracks.

FIG. 5D shows a perspective view 562 and a side view 564 of the robotwith the sensor module 400 detached from the elbow mount, illustratingthe modularity of the sensor module location. FIG. 5E shows a detailview of the first and second links 150 a-b and the elbow 150 c. Theelbow 150 c includes a mounting point for the sensor module 400.

The mounting point can include posts or other mechanical structureconfigured for, e.g., tool-less attachment and detachment of the sensormodule 400. The mounting point can include an electrical connector forproviding power to the sensor module 400 and for receiving sensor datafrom the sensor module 400 can carrying the sensor data to, e.g., acontroller on the robot.

As illustrated in FIG. 5E, the sensor module 400 is mounted to the elbow150 c by aligning pins, located on the sensor module 400, with matingholes 580 in the elbow 150 c. Screws 582 are used to fasten the sensormodule 400 to the elbow 150 c. A blind mating connector 584 providespower and signal to the sensor module 400. The sensor module 400 can beremoved by removing the screws and pulling the sensor module 400 off theelbow 150 c.

FIGS. 6A-B illustrate examples of the robot with the sensor modulemounted at a distal end of a manipulator arm. FIG. 6A shows a side view650 and a perspective view 652 of the robot in a morphology with bothfront and back flippers. The sensor module 400 is mounted on top of thegripper 170 using a picatinny mounting interface. The manipulator arm150 is deployed. This allows for a higher view point for the sensormodule 400 and thus a possibly improved situational awareness. FIG. 6Bshows a perspective view 654 and a side view 656 of a robot in amorphology with front flippers and the manipulator arm mounted forward.

FIGS. 7A-C illustrate examples of the robot in a configuration where themanipulator arm includes a first link and an elbow and lacks a secondlink. FIG. 7A shows a side view 750 and a perspective view 752 of therobot in a sensor-only configuration where the second link 150 b andgripper 170 are removed from the manipulator arm 150. The sensor module400 is mounted on the elbow 150 c. This allows for a lighter overallrobot for situations not requiring gripper manipulation with theenvironment while retaining the ability to pan/tilt the sensor module400. The elbow pitch DOF allows for the sensor module 400 to pitchup/down relative to the manipulator arm 150 while the turret yaw DOFprovides pan capability.

FIG. 7B shows a side view 754 of the robot in a morphology with frontflippers and a manipulator arm mounted forward and a sensor modulemounted on the manipulator arm. FIG. 7B also shows a side view 756 withthe sensor module detached. FIG. 7C shows a perspective view 758 of therobot in a morphology with front flippers and a manipulator arm mountedforward and a sensor module mounted on the manipulator arm.

FIG. 7C also shows a perspective view 760 with the sensor moduledetached.

FIG. 8 is a flow chart of an example method 800 for operating anunmanned ground vehicle. The method 800 can be performed by an operatorin the field. The method 800 includes mounting a sensor module to afirst location on a manipulator arm, e.g., an independently controllableelbow of the manipulator arm (802). The method 800 includes operatingthe robot and pivoting the elbow and the attached sensor module duringrobot operation (804). The method 800 includes re-mounting the sensormodule a second location on the manipulator arm, e.g. to a top of agripper on the manipulator arm using a picatinny rail, and then furtheroperating the robot with the sensor module at the second location (806).

Although specific examples and features have been described above, theseexamples and features are not intended to limit the scope of the presentdisclosure, even where only a single example is described with respectto a particular feature. Examples of features provided in the disclosureare intended to be illustrative rather than restrictive unless statedotherwise. The above description is intended to cover such alternatives,modifications, and equivalents as would be apparent to a person skilledin the art having the benefit of this disclosure.

The scope of the present disclosure includes any feature or combinationof features disclosed in this specification (either explicitly orimplicitly), or any generalization of features disclosed, whether or notsuch features or generalizations mitigate any or all of the problemsdescribed in this specification. Accordingly, new claims may beformulated during prosecution of this application (or an applicationclaiming priority to this application) to any such combination offeatures. In particular, with reference to the appended claims, featuresfrom dependent claims may be combined with those of the independentclaims and features from respective independent claims may be combinedin any appropriate manner and not merely in the specific combinationsenumerated in the appended claims.

What is claimed is:
 1. An unmanned ground vehicle comprising: a mainbody; a drive system supported by the main body, the drive systemcomprising right and left driven track assemblies mounted on right andleft sides of the main body; a manipulator arm pivotally coupled to themain body, wherein the manipulator arm comprises a first link coupled tothe main body, a rotatable member coupled to the first link, and asecond link coupled to the rotatable member, wherein the rotatablemember is configured to rotate independently of the first and secondlinks; and a sensor module mounted on the rotatable member, the sensormodule comprising one or more sensors at least partially located belowat least part of the second link when the second link is extendedupward.
 2. The unmanned ground vehicle of claim 1, wherein the rotatablemember is located below a distal end of the second link when the secondlink is extended upward.
 3. The unmanned ground vehicle of claim 2,further comprising a gripper or a head on the distal end of the secondlink.
 4. The unmanned ground vehicle of claim 1, wherein the sensormodule comprises a camera whose field of view extends horizontallyand/or upward in at least one rotational orientation of the rotatablemember when the one or more sensors are at least partially located belowat least part of the second link.
 5. The unmanned ground vehicle ofclaim 1, wherein the second link is detachable, and the unmanned groundvehicle is operable with the rotatable member and the sensor modulewithout the second link.
 6. The unmanned ground vehicle of claim 1,wherein the second link comprises a mount for the sensor module at adistal end of the second link, and the sensor module is detachable fromthe rotatable member and mountable on the mount.
 7. The unmanned groundvehicle of claim 6, further comprising a gripper or a head on a distalend of the second link, wherein the mount is configured for mounting thesecond module in a position in which the one or more sensors are atleast partially above the gripper and/or head.
 8. The unmanned groundvehicle of claim 7, wherein the one or more sensors comprise a camera,and the mount is configured for mounting the second module in a positionin which the camera is above the gripper and/or head.
 9. The unmannedground vehicle of claim 1, wherein the second link is pivotally coupledto the rotatable member, the first link includes a first motor forrotating the rotatable member, and the second link comprises a secondmotor for pivoting the second link about the rotatable member, such thatthe first and second motors are configured to control the positions ofthe sensor module and the second link with respect to the first link.10. The unmanned ground vehicle of claim 1, wherein the second link ispivotally coupled to the rotatable member, the first link includes afirst motor for rotating the rotatable member, the second link comprisesa second motor for pivoting the second link about the rotatable member,and the manipulator arm comprises a third motor for rotating therotatable member independently of the first and second links.
 11. Theunmanned ground vehicle of claim 1, wherein the manipulator arm iscoupled to the main body by a turret configured to provide yawcapability for the manipulator arm.
 12. An unmanned ground vehiclecomprising: a main body; a drive system supported by the main body, thedrive system comprising right and left driven track assemblies mountedon right and left sides of the main body; a manipulator arm pivotallycoupled to the main body, wherein the manipulator arm comprises a firstlink coupled to the main body, a rotatable member coupled to the firstlink, and a second link coupled to the rotatable member, wherein arotational orientation of the rotatable member is independent ofrotational orientations of the first and second links; a gripper or ahead on a distal end of the manipulator arm; and a sensor module mountedon the rotatable member, the sensor module comprising one or moresensors at least partially located below at least part of the gripper orhead when the manipulator arm is extended upward.
 13. The unmannedaerial vehicle of claim 12, wherein the sensor module is located belowthe gripper or head when the arm is extended upward.
 14. The unmannedaerial vehicle of claim 12, wherein the sensor module is located belowthe gripper or head when the second link is extended upward.
 15. Theunmanned ground vehicle of claim 12, comprising a motor dedicated torotate the rotatable member independently of the first and second links.16. The unmanned ground vehicle of claim 12, wherein the sensor modulecomprises a camera whose field of view extends horizontally and/orupward in at least one rotational orientation of the rotatable memberwhen the one or more sensors are at least partially located below atleast part of the gripper or head.
 17. The unmanned ground vehicle ofclaim 12, wherein the second link is detachable, and the unmanned groundvehicle is operable with the rotatable member and the sensor modulewithout the second link.
 18. A method for operating the unmanned groundvehicle of claim 1, the method comprising remotely controlling thevehicle to cause the vehicle to rotate the rotatable member to positionthe sensor module in a desired rotational orientation in which the oneor more sensors are at least partially located below at least part ofthe second link.
 19. A method for operating the unmanned ground vehicleof claim 12, the method comprising remotely controlling the vehicle tocause the vehicle to rotate the rotatable member to position the sensormodule in a desired rotational orientation in which the one or moresensors are at least partially located below at least part of thegripper or head.
 20. A method for operating an unmanned ground vehicle,the method comprising: mounting a sensor module to a first location on amanipulator arm pivotally coupled to a main body of the unmanned groundvehicle, wherein the manipulator arm comprises a first link coupled tothe main body, a rotatable member coupled to the first link, a secondlink coupled to the rotatable member, and one or more motors configuredto rotate the rotatable member independently of the first and secondlinks, and wherein mounting the sensor module to the first locationcomprises mounting the sensor module to the rotatable member; andremotely controlling at least one of the one or more motors to rotatethe rotatable member into a first position in which at least one sensorin the sensor module is at least partially below at least part of thesecond link.